/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.wrmsr.wava.util;

import javax.annotation.concurrent.Immutable;

import java.util.Optional;
import java.util.function.Supplier;

import static java.util.Objects.requireNonNull;

@Immutable
public class Box<T>
    implements Supplier<T>
{
    public final T value;

    public Box(T value)
    {
        this.value = requireNonNull(value);
    }

    public static <T, B extends Box<T>> Optional<T> optional(B box)
    {
        if (box != null) {
            return Optional.of(box.get());
        }
        else {
            return Optional.empty();
        }
    }

    @Override
    public final T get()
    {
        return value;
    }

    @Override
    public final boolean equals(Object o)
    {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        Box box = (Box) o;

        if (value != null ? !value.equals(box.value) : box.value != null) {
            return false;
        }

        return true;
    }

    @Override
    public final int hashCode()
    {
        return value != null ? value.hashCode() : 0;
    }

    @Override
    public String toString()
    {
        return getClass().getSimpleName() + "{value=" + value + '}';
    }
}
